Field of the Disclosure
The present disclosure relates to a communication unit.
Description of the Related Art
A communication unit that includes a power amplification module for amplifying the power of a radio frequency (RF) signal that is to be transmitted to a base station is employed in a portable terminal that utilizes a cellular phone communication network. In recent years, the number of users of portable terminals has increased tremendously and the number of frequency bands utilized by cellular phones has increased in order to handle the communication traffic created by these users. Therefore, it is required that portable terminals support these frequency bands.
In addition, from the viewpoints of design restrictions, profile reduction and size reduction of portable terminals, it is required that such communication units be reduced in size. Accordingly, for example, a power amplification module is used in which a plurality of power amplifiers, which support a plurality of communication schemes (modes) and a plurality of frequency bands, are integrated into a single module, as described in “TQM7M9050 data sheet”, TriQuint Corp., (online), web address: www.triquint.com/products/d/DOC-B-00000332.
The power amplification module disclosed in “TQM7M9050 data sheet”, TriQuint Corp., (online), web address: www.triquint.com/products/d/DOC-B-00000332 supports the second generation mobile communication system (2G) and the third/fourth generation mobile communication system (3G/4G). This power amplification module includes a power amplifier for a low frequency band (LB) that is a 1 GHz band of the global system for mobile communications (GSM) (registered trademark), which is the 2G communication standard, a power amplifier for a high frequency band (HB) that is a 2 GHz band of GSM, a power amplifier for an LB that is a 1 GHz band of 3G/4G and a power amplifier for an HB that is a 2 GHz band of 3G/4G.
In this power amplification module, the 3G/4G LB power amplifier covers two frequency bands that are band 5 (B5: transmission frequency band of 824 MHz to 849 MHz) and band 8 (B8: transmission frequency band of 880 MHz to 915 MHz). In addition, the 3G/4G HB power amplifier covers four frequency bands that are band 1 (B1: transmission frequency band of 1920 MHz to 1980 MHz), band 2 (B2: transmission frequency band of 1850 MHz to 1910 MHz), band 3 (B3: transmission frequency band of 1710 MHz to 1785 MHz) and band 4 (B4: transmission frequency band of 1710 MHz to 1755 MHz).
In recent years, as a technique for improving the downlink communication speed from a base station to a portable terminal, downlink carrier aggregation (hereafter, “DLCA”), which is a technique in which a plurality of frequency bands are simultaneously used in the downlink has been focused upon in long term evolution (LTE) advanced, which is a 4G communication standard. Consequently, a communication unit that is suitable for downlink carrier aggregation has been demanded.